Year	Percent
1961	50.57537
1962	50.5049
1963	50.46889
1964	50.43803
1965	50.40202
1966	50.36858
1967	50.33
1968	50.29399
1969	50.26312
1970	50.22506
1971	49.86651
1972	49.97557
1973	50.10417
1974	50.18185
1975	50.18185
1976	50.18185
1977	50.20757
1978	50.51467
1979	50.41179
1980	50.50541
1981	50.52085
1982	50.57486
1983	51.96636
1984	51.97202
1985	52.07721
1986	52.18293
1987	52.75341
1988	53.01114
1989	53.52504
1990	54.09141
1991	54.60737
1992	54.6192
1993	54.62075
1994	54.62589
1995	54.62846
1996	54.68762
1997	54.68762
1998	54.69534
1999	54.69585
2000	54.69791
2001	54.81108
2002	54.81108
2003	54.81108
2004	54.82137
2005	54.82137
2006	54.82137
2007	54.88824
2008	53.16752
2009	52.82132
2010	52.3712
2011	52.12171
2012	51.70503
2013	51.17724
2014	50.7976
2015	50.76262
2016	50.58669
2017	49.87062
2018	49.64943
2019	49.43851
2020	49.96939
2021	49.96322